(95b) The Effect of Chain Length of Feed on Hydrocracking Over Pt/SiO2-Al2O3 Catalyst

The hydrocracking of hydrocarbons with carbon number C₁₆ and C₂₈ and their mixture was studied over Pt promoted amorphous silica-alumina catalyst.  At various reaction conditions we determined the conversion, product selectivity, and the degrees of isomerization on the catalyst of each carbon number.  We found out that gas phase hydrocarbons (at the reaction conditions) passed through the catalyst bed much faster than liquid phase hydrocarbons so that essentially only the liquid hydrocarbons were converted. We found that at a low hydrocracking conversion range of wax, all the liquid phase reactants show about the same hydrocracking reactivity. So that we can conclude that the hydrocracking reaction depends not only on the carbon chain length but the phase of reactant at the reaction conditions if predominantly in the gas phase it is not or only slightly converted. Therefore the dependence of conversion on carbon number is directly related to the liquid/gas phase equilibrium.